A problem concerned with impulse wrenches is the difficulty to obtain an accurate and reliable measured value on the torque actually transferred to the screw joint and the pre-tension level actually obtained in the screw joint. Due to the fact that the tightening torque is transferred to the screw joint via short dynamic impulses, torque values measured by an in-line torque transducer does not give a true information of the pre-tension level obtained in the screw joint. The obtained torque measurements, however, quite well reflect the accomplished pre-tension level in the screw joint at repeated tightening of identical screw joints with the very same impulse wrench and do indicate quite accurately occurring deviations in the accomplished pre-tension of the screw joint.